Online code not working!

So our 2 pre-orders of PSP2 finally arrived in the shop today, and we picked them up, sealed. My girlfriend's online activation code worked first time on her PSP, but mine just keeps giving me an error saying the code is invalid. I have activated "game" and tried the usual suggestions like resetting the system and making sure the UMD isn't in, but it refuses to accept the code, saying it may not be correct or may no longer be valid.

No longer valid, from within a sealed case? Am I supposed to wait for the code to become active server-side or something? I can still get online by selecting "retry" after getting a user authentication error (sg4041), but having to sit through the error first is a hassle and I get the feeling I'm eventually going to be locked out/banned from online play, which was the #1 reason for my purchase.

Is anyone else having this problem?

Is the region of the game the same as the PSN account?

Ah, no it isn't, I'm visiting from England! Great suggestion, I'll try making a Canadian account.

Edit: Thanks Izuna, you found the problem!